ref: 0b8d09bb5198fb4d60d88e33b46862aec69f6e27
dir: /libstd/syscall+plan9-x64.s/
/* Ugly: Kernel is caller-save, Myrddin is callee-save. We need to preserve registers before entering the kernel. However, we also need SP to point to the start of the arguments. Luckily, the kernel doesn't touch our stack, and we have 256 bytes of gap if we get a note. */ TEXT sys$syscall+0(SB),1,$0 MOVQ BX,-16(SP) MOVQ CX,-24(SP) MOVQ DX,-32(SP) MOVQ SI,-40(SP) MOVQ DI,-48(SP) MOVQ BP,-56(SP) MOVQ R8,-64(SP) MOVQ R9,-72(SP) MOVQ R10,-80(SP) MOVQ R11,-88(SP) MOVQ R12,-104(SP) MOVQ R13,-112(SP) MOVQ R14,-120(SP) MOVQ R15,-128(SP) MOVQ 8(SP),RARG ADDQ $8,SP SYSCALL SUBQ $8,SP MOVQ -16(SP),BX MOVQ -24(SP),CX MOVQ -32(SP),DX MOVQ -40(SP),SI MOVQ -48(SP),DI MOVQ -56(SP),BP MOVQ -64(SP),R8 MOVQ -72(SP),R9 MOVQ -80(SP),R10 MOVQ -88(SP),R11 MOVQ -104(SP),R12 MOVQ -112(SP),R13 MOVQ -120(SP),R14 MOVQ -128(SP),R15 RET